To develop economical and high-performance water electrolyte supercapacitor electrodes, low-cost and cross-linked carbon nanofibers (CNFs) were prepared with an electrospinning method by using PAN, lignin, and PMMA as precursors. The addition of lignin not only reduces the cost of the carbon nanofibers but also increases the specific surface area of the CNFs by removing carbonyls, and phenol functional groups of lignin during thermal treatment. The effect of PMMA addition was investigated to prepare the optimal candidate for the supercapacitor electrodes. The results showed that the CNFs from PAN, PMMA, and lignin (PPLCNFs-x, x is the content of PMMA in the spinning solution) showed excellent electrochemical performance in alkaline aqueous electrolyte. PPLCNFs-0.5g showed specific capacitance of 233 F g(1-) at 0.5 A g(-1), an outstanding stability of 96.8% when it was cycled 50 000 times at 2 A g(-1), and it remained 54.5% of rate capability as current density raising from 0.5 to 100 A g(-1). The outstanding electrochemical performance of PPLCNFs-0.5g is expected as a consequence of the synergistic effect of larger specific surface area and cross-linked structure. The cross-linked structure ensures rapid transmission of electrons on the carbon nanofiber membrane, and the large specific surface area is conducive to charge storage. This method offers a new preparation approach for synthesizing high performance CNFs with low-cost, cross-linked structures.